From Ash to Cash: A Conversation about permanent CO2 storage using industrial waste with David Callejo from Resilco (Part II)

We spoke with David Callejo, the CEO and the Co-founder of Resilco, to understand their unique approach in reducing CO2 emission by recovering industrial waste materials, converting them into construction materials in which CO2 is permanently stored. Part II is about the technical side of things.

Written by 
Joanna Kolomanska
Edited by 
Victoria Chen-Englert
Updated on 
July 26, 2024
This article is an advertorial feature brought to you by our partners

(This is part II of our interview with David Callejo, the CEO and the Co-founder of Resilco. Resilco is an Italian startup founded at the end of 2019 that helps in CO2 emission reduction by recovering industrial waste materials, converting them into construction materials in which CO2 is permanently stored. Read part I here.)

B. The technical details behind Resilco's solutions

I would like to dive into the technical details of your solution. You have a few patents on CO2 mineralization and also on the treatment of fly ashes. Can you explain a little bit what fly ashes are?

So, let's start from the ground up. Fly ash isn't a specific material, it's a broad term for that super fine dust trapped by filters in chimneys across all sorts of industries. Basically, every industry has some kind of filter system on their smokestacks to catch dust particles. This dust usually contains a lot of minerals, and what ends up in the flying ash depends on the industry.

Treated and ground industrial residues

Ok, and you are able to capture and utilize fly ashes?

In waste-to-energy plants, for example, fly ash has minerals from the waste they burn, but also from the materials they add to adjust the acidity. Back in the 80s, we learned the hard way that acidic rain was destroying our forests. That's why almost every industrial chimney now has a system to control its acidity, often using calcium oxide or other high-pH materials. These materials get caught in the filters, creating a bit of a problem –  their high pH is making it hazardous waste.

But here's the interesting twist: this high pH waste actually reacts beautifully with CO2, turning it into carbonates. So, this fly ash becomes a really good material for recycling CO2. The key for us was figuring out how to make this reaction happen efficiently. Normally, this reaction would occur over time anyway, even if you just leave the fly ash sitting around for years. But we found a way to give the process a little nudge with minimal extra energy input, making it happen right away.

Treated and ground industrial residues.

So what's the magic behind this?

The key to our technology lies in the ingenious design of the reactor itself. We've patented both the reactor and the process that happens inside. This design includes how and where we inject CO2, along with the precise timing during the reaction.

We are able to harness a common physical phenomenon to our advantage. We deliver locally-focused energy precisely where needed, catalyzing rapid carbonation of materials without wasting energy in the surrounding areas. This targeted approach is key to optimizing both process duration and energy use. By making them happen at the exact right time and place, and with the right surrounding conditions, we can trigger all the necessary chemical reactions to occur simultaneously.

The beauty of this approach is its simplicity. We use standard, readily available components for most of the reactor.

A sample of material treated with the Resilco process was mixed with 50%of its weight in water and allowed to age.

That sounds very promising.  Can you elaborate on how your approach differs from competitors?

Absolutely. There are definitely other companies tackling fly ash, especially in Europe and the US. Some target smaller companies and focus on recovering specific minerals or salts. But here's the thing: over 90% of the remaining fly ash ends up back in landfills.

What sets us apart is our focus on complete utilization -- we're the only ones capturing 100% of the fly ash. Others might target specific minerals or remove things like salts, leaving the rest for landfills, but we offer a solution for the entire fly ash stream.

Also, most competitors rely on high-pressure, high-temperature methods that are environmentally unsustainable. They require more energy (which emits CO2) than the CO2 storage they achieve. Additionally, some use chemicals for extraction, which creates regulatory hurdles and environmental concerns.

We avoid all of that. We use low-energy techniques and a completely chemical-free approach. In fact, we're one of the few, maybe even the only ones, doing this whole process in a carbon-negative way. We use room temperature, normal pressure, and no fancy chemicals. We don't want to introduce new problems while solving the existing one. These features, I believe, are the key advantages that set our technology apart.

What is your technology readiness level?

We've built an industrial-scale reactor right here in our facility. We opted for the smallest possible industrial version to demonstrate the technology's capabilities using readily available industrial components.

We're at the point where we're ready to sell the entire system, not just the reactor itself. We're currently conducting demonstrations with potential customers in Italy, our primary market. We present them not only the reactor but also the final processed material.

The good news is, we already have customers lined up for the processed fly ash, having tested and validated its quality. Our immediate goal is to close deals on the first two full-scale industrial plants this year.

C. Last but not least

What else should your potential partners or customers know about Resilco?

We encourage open dialogue and invite customers to discuss their needs with us, as this often leads to discovery. . Our philosophy revolves around transparency and openness in technology discussions — something our partners might say we take to an extreme. Through these interactions, we sometimes encounter novel materials we hadn't considered before, which expands the horizon of our work.  

Thank you, David, for the interview!

(Missed Part I, where David talks about the business aspects of Resilco? Read it here.)

Ready to supercharge your sales pipeline?